224 



Journal of Agricultural Research 



Vol. VI, No. 6 



Figure 22. — Lateral strain-gauge readings were taken on points paral- 

 lel to the supports over the middle third of the slab, and these are plot- 

 ted on base lines both parallel and perpendicular to the supports. The 

 groups of closely drawn parallel lines serve only to connect each curve 

 with its base line. Compression values of the deformations are plotted 

 either to the left or below the base lines, and to the right or above, for 

 values of tension in the concrete. The variations in these lateral de- 

 formations are the reverse of those of the longitudinal deformations 

 shown in figures 20 and 21 ; they are more critical along lines parallel to 

 the supports. 



Figure) 23. — The data of the last three figures have been collected and 

 plotted as " iso-deformation lines," giving a series of lines or contours 



32 FT. 



i _ 



Fig. 19. — Diagram showing efiect of breaking load on slab 934. 



which represent equal deformations in the concrete on the top of the 

 slab. The lines, as drawn, are averages of the plotted points. Figure 

 23 (also fig. 26) is more for academic interest and should be of service in 

 the theoretical consideration of stress distribution. 



Figures 24 and 25. — These figures are similar to figures 20 and 21, and 

 are plotted in the same manner, except that they represent the distri- 

 bution of deformations under a working load of 40,000 pounds applied 

 at four points. No lateral deformation readings are shown. The load 

 points are indicated in figure 25. The local effect at the loading points 

 is very pronounced. 



Figure 26.— The data of the last two figures mentioned have been here 

 collected and show the "iso-deformation lines" for the 4-point loading 

 of 40,000 pounds, total. (See description of figure 23.) 



